View full sizeAP Photo/Washington State University, Len ZoeliThis undated image provided by Washington State University shows an endangered pygmy rabbit in the wild in eastern Washington.

SPOKANE -- The tiny Columbia Basin pygmy rabbit remains an endangered species and threats to the animal have increased in the past five years.

That's the conclusion today of the U.S. Fish and Wildlife Service's five-year review of efforts to save the animals.

The study found increased risk from disease in captivity; the rabbits getting used to captive conditions and becoming less capable of surviving in the wild; and loss of genetic uniqueness due to interbreeding.

The pygmy rabbit is the smallest rabbit in North America, and can fit in a man's hand. It is one of only two rabbit species in North America that digs its own burrows.